How do you track insider trading with Form 4?
Form 4 is the report a company's officers, directors and holders of more than 10% file with the SEC when they buy or sell its shares. It is due within 2 business days of the trade (Investor.gov). Search filings free on EDGAR, then filter for open market purchases, code P.
What are Forms 3, 4 and 5?
They are the 3 ownership reports for insiders under Section 16 of the Exchange Act. The SEC's investor bulletin sets out the timing (Investor.gov):
| Form | When it is filed | What it reports |
|---|---|---|
| Form 3 | Within 10 days of becoming an insider | Initial holdings |
| Form 4 | Within 2 business days of a transaction | Each change in holdings, with amount and price per share |
| Form 5 | Within 45 days after the company's fiscal year end | Transactions that were exempt from Form 4 or were not reported on it |
The 2-business-day deadline has applied to transactions since 29 August 2002, replacing a monthly deadline (Paul Weiss, 2002). A trade on a Tuesday is due by the close of Thursday.
Step 1. Find the filings on EDGAR
Search the company in SEC EDGAR company search and filter the form type to 4. Insider filings appear under the company and under each insider's own name, so you can also search a director to see trades across every board seat they hold. EDGAR's latest filings page lists new Form 4s across all companies as the SEC accepts them. For bulk work, the SEC publishes Insider Transactions Data Sets, extracted from Forms 3, 4 and 5 and updated quarterly (SEC).
Step 2. Read who filed and their role
The top of the form names the reporting person, the issuer and the relationship: director, officer with title, 10% owner or other. A chief executive or chief financial officer buying carries more weight than a director receiving an annual grant.
Step 3. Read the transaction code
Table I covers shares and Table II covers options and other derivatives. Each line carries a code. The ones you will see most:
| Code | Meaning | How to read it |
|---|---|---|
| P | Open market or private purchase | The insider spent their own money; the strongest signal |
| S | Open market or private sale | Needs context: tax, diversification, a plan |
| A | Grant or award from the company | Pay, not a decision to buy |
| M | Exercise or conversion of an option or other derivative | Often followed by a sale or by code F |
| F | Shares withheld to pay the exercise price or tax | Routine; not a sale in the market |
Codes P and S as defined on the SEC's Form 4 (SEC EDGAR, 2002 Form 4); codes A, M and F as summarised by Arkolith.
Step 4. Check for a 10b5-1 plan
Since 1 April 2023, Form 4 has a checkbox showing whether a trade was made under a plan meant to meet the Rule 10b5-1(c) defense, with the plan's adoption date given in the explanation of responses (Hunton). Sales under a plan set months earlier say less about the insider's current view than a sale made without one.
Step 5. Look at the pattern across insiders and time
A single sale tells you little. Several insiders buying in the open market within a few weeks, or a chief executive buying after a sharp fall, carries more information. Read the footnotes too: they explain weighted average prices, indirect holdings through trusts and funds, and gifts. If you apply only one filter to insider data, make it code P (Arkolith).
Where does Tamarly Intelligence help?
Tamarly Intelligence is Tamarly's research platform on companies, funds, countries and markets, built from official filings and open data. It reads SEC EDGAR filings and links every figure to the filing it came from; company pages show institutional holders from 13F filings. Tamarly shows no market prices and no trading tools, so it will not score insider trades against the share price. For larger holders, see how to read a Schedule 13D and how to find who owns a company; for free trackers, see free SEC filing search tools.
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Frequently asked questions
How long do insiders have to file a Form 4?
2 business days after the transaction (Investor.gov). Some transactions that are exempt from Form 4 can be reported later on Form 5, within 45 days after the company's fiscal year ends.
Is insider buying a good signal?
It can be a useful prompt for research, never a reason on its own. Open market purchases, code P, are the trades where insiders chose to spend their own money. Grants, option exercises and tax withholding are pay mechanics and carry little information.
Can I search Form 4 filings for free?
Yes. SEC EDGAR lists every Form 4 by company and by insider, at no cost. The SEC also publishes quarterly Insider Transactions Data Sets drawn from Forms 3, 4 and 5 (SEC), and free trackers build screens on top of the same filings.
About the author. Melvine Manchau is the founder of Tamarly and author of the Tamarly Newsletter. He previously worked at PwC, Salesforce, BlackRock/eFront and Lazard.
About Tamarly Research. Tamarly Research is part of Tamarly Media, which holds no investment positions. Tamarly is a New York research house that studies how AI is changing regulated institutions.